首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   296篇
  免费   6篇
  国内免费   24篇
安全科学   15篇
环保管理   7篇
综合类   243篇
基础理论   44篇
污染及防治   9篇
评价与监测   1篇
社会与环境   3篇
灾害及防治   4篇
  2022年   1篇
  2021年   1篇
  2020年   4篇
  2019年   2篇
  2018年   2篇
  2016年   4篇
  2015年   2篇
  2014年   7篇
  2013年   10篇
  2012年   11篇
  2011年   26篇
  2010年   11篇
  2009年   21篇
  2008年   17篇
  2007年   19篇
  2006年   15篇
  2005年   14篇
  2004年   22篇
  2003年   25篇
  2002年   26篇
  2001年   16篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   13篇
  1994年   13篇
  1993年   4篇
  1992年   3篇
  1991年   5篇
  1990年   3篇
  1989年   4篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
  1983年   3篇
  1982年   4篇
  1981年   4篇
排序方式: 共有326条查询结果,搜索用时 15 毫秒
71.
72.
The ability to examine the structure of the fetal heart in real-time started over 30 years ago now. The field has seen very great advances since then, both in terms of technical improvements in ultrasound equipment and in dissemination of operator skills. A great deal has been learnt about normal cardiac function in the human fetus throughout gestation and how it is affected by pathologies of pregnancy. There is increasing recognition of abnormal heart structure during routine obstetric scanning, allowing referral for specialist diagnosis and counselling. It is now possible to make accurate diagnosis of cardiac malformations as early as 12 weeks of gestation. Early diagnosis of a major cardiac malformation in the fetus can provide the parents with a comprehensive prognosis, enabling them to make the most informed choice about the management of the pregnancy. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
73.
74.
75.
Congenital diaphragmatic hernia (CDH) can be associated with genetic or structural anomalies with poor prognosis. In isolated cases, survival is dependent on the degree of lung hypoplasia and liver position. Cases should be referred in utero to tertiary care centers familiar with this condition both for prediction of outcome as well as timed delivery. The best validated prognostic indicator is the lung area to head circumference ratio. Ultrasound is used to measure the lung area of the index case, which is then expressed as a proportion of what is expected normally (observed/expected LHR). When O/E LHR is < 25% survival chances are < 15%. Prenatal intervention, aiming to stimulate lung growth, can be achieved by temporary fetal endoscopic tracheal occlusion (FETO). A balloon is percutaneously inserted into the trachea at 26–28 weeks, and reversal of occlusion is planned at 34 weeks. Growing experience has demonstrated the feasibility and safety of the technique with a survival rate of about 50%. The lung response to, and outcome after FETO, is dependent on pre-existing lung size as well gestational age at birth. Early data show that FETO does not increase morbidity in survivors, when compared to historical controls. Several trials are currently under design. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
76.
77.
78.
79.
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号